Plate burner



' Nov. 13, 1945. F, T, POWERS 2,388,762

PLATE BURNER Filed Feb. 11, 1943 ATTORNEY Patented Nov. 13, 1945 U N ITED STATE S PATE N T O F'FI'C E :PLATE BURNER Frank T..Powers, GlenCove, .Y. Application February 11, 1943, Serial No. 475,570

(01. zsa-s) 2 Claims.

The present invention relates to plate burners and more particularly tonovel and useful improvements in machines for heating and melting theresinous powdered material-applied to a partial-ly etched photoengravedplate between the various etching steps.

Objects and advantages of the invention will be set forth in parthereinafter and in part will be obvious hereifrom, or may be learned bypractice with the invention, the same being realized and attained by-means of the instrumentalities "and combinations pointed out in theappended claims,

, The invention consists in the novel parts, constructions,arrangements, combinations and improvements herein shown and described.

The accompanying drawing, referred to herein and constituting a parthereof, illustrates one embodiment -of the invention, and together withthe description, serves to explain the principles of the invention.

Of the-drawing:

Figure 1 is a diagrammatic side "elevation of a typicaland illustrativeembodiment of the invention;

Figure 2 is a sectional -view taken on the line 2-2 of Fig. 1; and

Figure 3 is a sectional view looking upwardly "and takenon' the 'line-33 of Fig. 2. r

The present inventionhas forits object the provision of a novlandimproved plate burn- -ing machine foruse in the photoengraving process.-A further object of'the present invention is the provision of animproved apparatus for heating andmeltingthe powdered resinous ma-"terial "applied to the surface of the plate at various stag-es in'theprocess of etching a'line or halftbne engraving. The invention alsoprovides an apparatus for burning the surface of the platewithoutheating the-metal of the plate to a relative high temperature.Another object of the invention is the provision of an improvedburning-in apparatus "which is capable of producing improvedphotoengraved plates.

In 'the process of p'hotoengraving, the plate of copper, zinc or othermetal which has been provided with a developed print of photosensitiveresist or enamel and *has been given a light -pre'liminaryetch, ispowdered four separate times in different directions with dragons bloodor other suitable resin, and *after each powdering operation, theplatemust be heated to melt the resin and cause the resin powder to adhere toithe sides :of "the etched portions of the plate,:thereby'strengtheningthe'resist and allowing the 5 plate 'tobe furtheretched without serious undercutting. This process is well known, andformsof apparatusfor carrying it out is shown in my :prior Patents No.1,520,720 and No; 2,017,510. .In certain respects the present inventionis an improve- *ment upon the'apparatus of my prior patents, but

it is also applicable to other forms of apparatus for the burning in ofphotoen'graved plates.

In accordance with the present invention, means are provided forsupporting a partially etched and powdered photoengraved plate, such asa half-tone 'or line photo-engraving, and this plate is supported withits partially etched and powdered surface facing upwardly. Immediatelyabove the surface of the plate and extending across the plate, and ifdesired, covering the entire surface of the plate, are a plurality ofradiant gas burners facing downwardly towards the etched and powderedsurface of the plate, and these burners are preferably positionedclosely adjacent to each other so as to form almost a continuousuniformly heated surface which radiates an intense heat on to the upper"surface of the plate bearing the enamel and the powdered dragons bloodor other resin to be melted. I

Where the plate is positively moved at a substantially uniform ratebeneath the heater, only a narrow series of burners extending across theentire path of movement of the plate need be provided, but if desired,the burners may extend over an area which is somewhat larger than thearea of the plate to be burned in. I These radiant gas heaters arepreferably supplied with pre-mixed gas and air under considerablepressure, and means are preferably provided for supplying theburnerswith this premixed fuel at a relatively low rate which maintainsthe burners hot and ready to come to incandescence with only a minimumtime delay after the rate at which fuel is supplied is increased whenthe plate is to be burned in. Where the plate is to be manually placedbeneath the radiant heaters, the fuel supply may be manually controlled,but when the plates are to be fed automatically into and out of theheater, automatic means are preferably provided for increasing anddecreasing the supply of premixed fuel in timed relation with themovement of the plate withrespect to the burners. Suitable refractoryinsulating material is preferably provided above and beneath the plateand burners and at its sides to conserve the heat and prevent damage tothe remainder of the apparatus.

Referring now in detail to the illustrative embodiment of the inventionas shown in thedrawing, where it is shown as forming a part of anautomatic powdering and burning in machine, there is provided a supportfor the partially etched and powdered photoengraved plates, comprising achain conveyor l having rollers I2 which run on the longitudinallyextending angle iron tracks l4, the two chain portions beinginterconnected by means of plate supporting cross bars l6. The chains IDare driven at a relatively low speed and the plate is received on theconveyor from the powdering apparatus after each powdering operation hasbeen completed, and conveys the plate through theburning in portion ofthe apparatus and thence to the cooling apparatus. The powdering andother portions of the completely automatic apparatus are not shown asthey form no part of the present invention.

For burning in the powder applied to the sides of the dots or lines ofthe half tone or line photoengraving there is provided a burning-inchamber having a bottom 26 and side and end walls 22, of refractorymaterial such as fire brick, the end walls 24 being provided with anarrow slot 25 through which the conveyor chain introduces and removesth partially etched and powdered plates.

Immediately above the conveyor chain, and spaced a convenient distancefrom the plates carried by the conveyor chain are provided a pluralityof radiant gas burners 26 which are fed with premixed fuel through thepipe 30 and the main supply pipes 32. These burners 26 are preferablydirected downwardly so that the heat radiated from them falls directlyupon the partially etched and powdered surface of the photoengravedplates I! as these plates are carried along by the conveyor. Theindividual radiant burners 26 ar preferably spaced closely together soas to form a substantially continuous, highly heated radiant surfacewhich is of a width corresponding to the maximum width of plate to beburned in.

As illustratively embodied the heaters are formed of a hexagonal pieceof refractory material 34 enclosed within a metallic supporting sheath36, the inner surface of the refractory being deeply dished to provide acombustion surface for the burning fuel which issues from the relativelysmall flutes or slots in the central portion 31 of the burner.

Means are also provided for maintaining the radiant burners 26 at amoderate heat so as to conserve gas, reduc the average temperature ofthe burning in apparatus, and increase the speed of operation, and forthis purpose the gas line 32 is provided with a valve 38 in addition tothe main shut-off valve 46. Valve 38 is normally partially open so as toallow only a moderate quantity of premixed fuel to be supplied to theburners, and means are provided for increasing the flow of fuel to amaximum by fully opening the valve 38 so as to produce the intense heatnecessary for the quick burning in of the powdered resinous material onthe face of the plate.

In order to automatically effect the control of the fuel supplied to theburners 26 in timed relation with the movement of the plates, theconveyor chain I0 is provided with upwardly extending members 42immediately adjacent the trailing edge of the plates l1, and cooperatingmeans are provided for opening the valve 38 to its maximum a short timebefore the plate enters the burner housing 20, 22, 24, and for reducingth opening of valve 38 as soon as the plate has been completely burnedin. These means may comprise a lever 44 positioned well in advance ofthe burners and connected through link 46, bell crank 41 and link 48 tothe valve operating lever 49 so that the valve 38 is opened suflicientlyin advance of the introduction of the plate beneath the burners to allowthe burners to attain their full radiant intensity, and another set oflevers 56, 5| and links 52 and 53 are connected with the lever 49 so asto be operated by the projection 42 to reduce the flow of fuel after theplate has been burned in.

In the operation of the illustrative embodiment of the presentinvention, the previously partially etched and powdered photoengravedplate is delivered to the conveyor chain In with its etched and powderedface upwardly, and the trailing edge of the plate closely adjacent to aprojection 42. As the chain moves, the projection 42 causes th valve 38to be opened to maximum, and the already moderately heated radiantburners 26 are supplied with additional fuel to bring them to theirmaximum intensity of radiation by the time the leading edge of th plateI1 is introduced into the burning in chamber beneath the radiant burners26.

As the plate passes beneath the burners 26, its powdered and partiallyetched surface is quickly and uniformly heated by the radiant heat fromthe burners, and this heat is applied directly to the powder, causing itto be quickly melted and Without substantial heating of the relativelylarge mass of the plate ll, while at the same time any excess powder andany powder not on the sides of the dots or lines is blown away by therelatively intense flow of air and gases from the burners. The plate iscontinuously progressed past the burners 26 and out into the atmospherewhere it may be further cooled if desired, and as the plate iscompletely withdrawn from the burning-in chamber, the valve 38 isautomatically moved to its partially closed position to reduce thesupply of fuel so that the burners are maintained moderately hot untilthe next plate is to be burned in.

By reason of the fact that the heat is directly applied to the surfaceof the plate for only a rela, tively short time, and from a relativelyintense radiant source, the powdered resinous material is almostinstantaneously melted and this is accomplished without injuring thestrength of the metal plate I! and without causing it to be warped byexcessive heating. Once the resin has been melted, the resin is setalmost immediately 7 instead of its dripping or flowing downwardly andinto the intagliated spaces between adjacent dots or lines. Therebycleaner working photoengravings may be produced, as only the sides ofthe lines or dots are coated with this resinous material, any excesspowdered resin lying on the bottom of the intervening spaces being blownaway by the relatively intense air circulation created by the flames ofthe radiant heaters. This is in contrast to the conventional apparatusheretofore usedin which the heat was applied to the plate as a whole, orto the underside of the plate, resulting in a heating of the powderedresinous material at the same rate as the heating of the plate. Suchconventional apparatus is also disadvantageous in the quality of workproduced, as well as in the fact that it was usually necessary tostraighten out the plates after they had been warped by the relativelyintense heat applied to them.

The invention in its broader aspects is not limited to the specificmechanisms shown and described but departures may be made therefromwithin the scope of the accompanying claims without departing from theprinciples of the invention and without sacrificing its chiefadvantages.

What I claim is:

1. In a plate burner for photoengraving use, the combination of aplurality of radiant gas burners, a moving support for moving an etchedand powdered plate beneath the burners, a valve controlling the supplyof fuel to the burners and means operated by the moving support forcontrolling the valve to increase the fuel supply to the burners priorto the passage of the plate beneath the burners, and further meansoperated by the moving support for controlling the valve to decrease thefuel supply to the burners after the passage of the plate beneath theburners.

2. In a plate burner for photoengraving use, the combination of aplurality of radiant gas burners, a moving support for moving an etchedand powdered plate beneath the burners, and a valve controlling thesupply of fuel to the burners and normally supplying a sufiicient amountof fuel to keep the burners moderately hot, means operated by the movingsupport for controlling the valve to increase the fuel supply to theburners prior to the passage of the plate beneath the burners, andfurther means operated by the mov- .ing support for controlling thevalve to decrease the fuel supply to the burners after the passage ofthe plate beneath the burners.

FRANK T. POWERS.

